HEST describes error sources in detail; communicating operationalparameters (i.e. severity levels, masking bits, and threshold values)to OS as necessary. It also allows the platform to report errorsources for which OS would typically not implement support (forexample, chipset-specific error registers).

HEST information may be needed by other subsystems. For example, HESTPCIE AER error source information describes whether a PCIE root portworks in "firmware first" mode, this is needed by general PCIE AERerror subsystem. So a public HEST tabling parsing interface isprovided.